1. Technical Field
The present invention relates to a liquid ejecting head unit for an ink jet recording head or the like that applies pressure fluctuations to a pressure chamber that communicates with a nozzle and causes a liquid in the pressure chamber to be ejected through the nozzle.
2. Related Art
Ink jet recording heads (called simply “recording heads” hereinafter) used in image recording apparatuses such as ink jet recording apparatuses (called simply “printers” hereinafter), coloring material ejecting heads used in the manufacture of color filters for use in liquid-crystal displays and the like, electrode material ejecting heads used in the formation of electrodes in organic EL (electroluminescence) displays and FEDs (front emission displays) and the like, bioorganic matter ejecting heads used in the manufacture of biochips (biochemical devices), and so on can be given as examples of liquid ejecting heads that eject a liquid within a pressure chamber as liquid droplets through a nozzle by causing a pressure fluctuation to occur within the pressure chamber.
For example, the stated recording head is configured by attaching, to a head case manufactured from a resin, a flow channel unit in which a serial liquid flow channel extending from a reservoir, through the pressure chamber, and to the nozzle is formed, an actuator unit including a pressure generation element capable of causing fluctuations in the volume of the pressure chamber, and so on. Furthermore, a nozzle plate in which a plurality of nozzles are provided is affixed to the stated flow channel unit.
The liquid ejected from such a recording head has a viscosity that is suitable for ejection, such as, for example, approximately 4 mPa·s at normal temperatures. The viscosity of a liquid correlates with the temperature thereof, while the liquid tending to become more viscous at lower temperatures and less viscous at higher temperatures. Although a recording head provided with a heater that heats the liquid is known as a head that allows the viscosity of the liquid to be ejected from the nozzles to be set to a value suitable for ejection regardless of the ambient temperature, it is necessary to change the amount of heat generated by this heater in accordance with the temperature of the flowing liquid. Accordingly, a configuration has been proposed in which, in order to accurately ascertain the temperature of the liquid, a flow channel member through which a liquid flows is formed of a metal having a favorable thermal conductivity, such as aluminum, which reduces the temperature difference between the flow channel member and the liquid, and a temperature sensor (a temperature measurement device) that is mounted on the flow channel member indirectly measures the temperature of the liquid (for example, see JP-A-2010-131943).
Incidentally, in a recording head such as that described above, it takes time for heat to be transferred through the entirety of the metal and for the metal to reach a set temperature, and thus it takes time before an accurate liquid temperature can be obtained. Furthermore, because the flow channel member is formed of a metal, it is difficult to form the flow channel member, and also leads to an increase in costs. This also increases the weight of the recording head.